As an image forming method capable of forming a high quality image similar to a color photograph, a dye thermal transfer recording method is the subject of attention. Usually in an image forming apparatus utilizing the dye thermal transfer recording method, an endless recording intermediate belt is used, which is a strip-shaped belt with two ends thereof joined. The recording intermediate belt is wrapped around a platen drum so as to travel around a continuous path at a prescribed speed. An outer circumferential surface of the recording intermediate belt has a dye fixing layer transferred and stacked thereon. An image is formed in a prescribed image formation area on the dye fixing layer.
A plurality of image forming sections respectively for forming images of different colors are located around the platen drum. A recording head provided in each image forming section is pressed onto an image forming area of the dye fixing layer, and an image forming operation is performed based on an image signal. Thus, images of different colors are formed on the image forming area of the dye fixing layer. A full-color image is formed on the dye fixing layer by the images of different colors formed by the image forming sections.
The full-color image formed on the dye fixing layer of the recording intermediate belt is transferred onto the recording paper together with the dye fixing layer. The recording paper is drawn from, for example, a roll of a recording paper. The recording paper having the full-color image transferred thereon is cut into a prescribed size by a cutter and discharged to the outside of the apparatus.
In such an image forming apparatus, the recording intermediate belt travels around the path at a prescribed speed due to a high frictional force with an elastic body made of, for example, a rubber layer provided on the outer circumferential surface of the platen drum. The image forming operation is performed by the recording head of each image forming section being pressed onto the recording intermediate belt which is traveling around the path. Thus, an image is formed. Therefore, in the case where while an image is being formed on the recording intermediate belt by the recording head of one of the image forming sections, the recording head of another image forming section is pressed onto the recording intermediate belt or the recording head of another image forming section starts or stops the image forming operation, a load fluctuation or the like can occur to the recording intermediate belt. When the load fluctuation or the like occurs, the image which is being formed by the recording head may have color non-uniformity or the like, which prevents formation of a clear full-color image.
In order to allow the recording intermediate belt to travel around the path at a prescribed speed by the platen drum which is driven to rotate, the recording intermediate belt needs to be wrapped around the platen drum at a high tension. However, when the recording intermediate belt is wrapped around the platen drum at a high tension, the recording intermediate belt is subjected to a large stress. This prevents the recording intermediate belt from being used for a long period of time stably, which necessitates the recording intermediate belt to be frequently replaced.
The recording intermediate belt travels around the path at a prescribed speed by a high frictional force generated by the elastic body made of, for example, rubber, which is provided on the outer circumferential surface of the platen drum. However, depending on the size precision of the recording intermediate belt, the size precision of the parts including the platen drum, assembly precision of the parts, and the like, the recording intermediate belt may travel around the path in a meandering manner. When the recording intermediate belt meanders, the images of different colors which are formed by the respective image forming sections are positionally offset from each other and thus the resultant full-color image may have color non-uniformity or the like.
After the full-color image formed on the recording intermediate belt is transferred onto the recording paper drawn from the roll of recording paper, the recording paper is peeled off from the recording intermediate belt. Then, the recording paper is cut into a prescribed size by a cutter. The recording paper is usually transported to a direction which is different from the transportation direction of the recording intermediate belt. However, in the structure of the apparatus in which the recording paper is peeled off from the recording intermediate belt by transporting the recording paper in a direction which is different from the transportation direction of the recording intermediate belt, the recording paper having the full-color image transferred thereon may not be surely peeled off from the recording intermediate belt.
The recording paper which has been peeled off from the recording intermediate belt is cut by a cutter. When the cutter contacts the recording paper, a load fluctuation or the like occurs to the recording paper and may be conveyed to the recording intermediate belt. In this case also, the image formed on the recording intermediate belt by each image forming section may have color non-uniformity or the like.
The recording intermediate belt which travels around the path by the high frictional force between the recording intermediate belt and the platen drum is worn out and deteriorates over time, and thus is required to be replaced with a new recording intermediate belt.
In this case, the platen drum and each image forming section are supported between a front chassis and a rear chassis. In order to allow a new endless recording intermediate belt to be wrapped around the platen drum in replacement with the old endless recording intermediate belt, it is necessary to separate the chassis which supports one end of the platen drum from the chassis which supports the image forming sections and the like, such that the new endless recording intermediate belt is inserted around one of the chassis.
However, in such a structure in which the chassis which supports the platen drum is separated from the chassis which supports the other chassis, it is not easy to reassemble the two chassis. Therefore, the platen drum may not be positioned with respect to each imaging section with high precision.
A plurality of image forming sections are provided around the platen drum, and an image transfer section for transferring an image formed on the recording intermediate belt onto the recording paper and other elements are provided around the recording intermediate belt. Therefore, the operation of causing the new recording intermediate belt to be wrapped around the platen drum needs to be done in a limited space and thus is difficult.
For solving these inconveniences, the present invention has an objective of providing an image forming apparatus which does not cause color non-uniformity to an image formed on a recording intermediate belt and allows formation of a clear image.
Another objective of the present invention is to provide an image forming apparatus in which the recording intermediate belt is not subjected to a large tension and thus is usable for a long period of time stably.
Still another objective of the present invention is to provide an image forming apparatus which can suppress the recording intermediate belt from meandering and allow the recording intermediate belt to run stably.
Still another objective of the present invention is to provide an image forming apparatus in which a recording paper can be surely peeled off from the recording intermediate belt, the load fluctuation on the recording paper which is caused when cut by a cutter or the like is not conveyed to the recording intermediate belt, and thus color non-uniformity does not occur to an image formed on the recording intermediate belt.
Still another objective of the present invention is to provide an image forming apparatus in which recording intermediate belts can be easily replaced, and the chassis which supports the platen drum can be easily positioned with respect to the other chassis.
The present invention has an objective of providing a recording intermediate belt mounting jig for an image forming apparatus for allowing easy replacement of recording intermediate belts.